Re: i.mx6 camera interface (CSI) and mainline kernel

[Hans Verkuil <hverkuil@xs4all.nl>]

On 06/02/2016 03:29 PM, Tim Harvey wrote:
> On Wed, Mar 9, 2016 at 4:12 PM, Steve Longerbeam
> <steve_longerbeam@mentor.com> wrote:
>> On 03/09/2016 02:44 PM, Tim Harvey wrote:
>>> On Tue, Mar 8, 2016 at 6:06 PM, Steve Longerbeam
>>> <steve_longerbeam@mentor.com> wrote:
>>>> On 03/07/2016 08:19 AM, Tim Harvey wrote:
>>> <snip>
>>>>
>>>> Hi Tim, good to hear it works for you on the Ventana boards.
>>>>
>>>> I've just pushed some more commits to the mx6-media-staging branch that
>>>> get the drivers/media/i2c/adv7180.c subdev working with the imx6 capture
>>>> backend. Images look perfect when switching to UYVY8_2X8 mbus code instead
>>>> of YUYV8_2X8. But I'm holding off on that change because this subdev is used
>>>> by Renesas targets and would likely corrupt captured images for those
>>>> targets. But I believe UYVY is the correct transmit order according to the
>>>> BT.656 standard.
>>>>
>>>> Another thing that should also be changed in drivers/media/i2c/adv7180.c
>>>> is the field type. It should be V4L2_FIELD_SEQ_TB for NTSC and V4L2_FIELD_SEQ_BT
>>>> for PAL.
>>>>
>>>> Steve
>>>>
>>>>
>>> Steve,
>>>
>>> with your latest patches, I'm crashing with an null-pointer-deref in
>>> adv7180_set_pad_format. What is your kernel config for
>>> CONFIG_MEDIA_CONTROLLER and CONFIG_VIDEO_V4L2_SUBDEV_API?
>>
>> Right, I thought I fixed that, I was passing a NULL pad_cfg for
>> TRY_FORMAT, but that was fixed. Maybe you fetched a version
>> of mx6-media-staging while I was in the middle of debugging?
>> Try fetching again.
>>
>> I tried with both CONFIG_MEDIA_CONTROLLER and
>> CONFIG_VIDEO_V4L2_SUBDEV_API enabled and both disabled, and
>> I don't get the null deref in adv7180_set_pad_format.
>>
>>
>>>
>>> Your tree contains about 16 or so patches on top of linux-media for
>>> imx6 capture. Are you close to the point where you will be posting a
>>> patch series? If so, please CC me for testing with the adv7180 sensor.
>>
>> I guess I can try posting a series again, but there will likely be push-back from
>> Pengutronix. They have their own video capture driver for imx6. Last I heard (a while ago!)
>> their version did not implement scaling, colorspace conversion, or image rotation via
>> the IC. Instead their driver sends raw camera frames directly to memory, and image
>> conversion is carried out by separate mem2mem device. Our capture driver does
>> image conversion (scaling, CSC, and rotation) natively using the IC pre-processing channel.
>> We also have a mem2mem device that does conversion using IC post-processing,
>> which I have included in mx6-media-staging.
>>
>> Also IIRC they did some pretty slick stuff with a video bus multiplexer subdev, which
>> can multiplex video from different sensors either using the internal mux in the SoC,
>> or can control an external mux via gpio. Our driver only supports the internal mux,
>> and does it with a platform data function.
>>
>> But like I said, I don't what the latest status is of the Pengutronix video capture support.
>>
>> Btw, I just pushed an update of mx6-media-staging that implements vidioc_[gs]_selection.
>>
>> Steve
>>
>>
> 
> Steve,
> 
> Some time has passed without any IMX6 CSI drivers or response from
> Pengutronix and Hans has agreed to add either/both drivers to staging.
> Do you have time to rebase and re-post your driver(s)? Maybe that will
> get the ball rolling on this final huge missing feature for the IMX6
> in mainline.

Right. All that is needed is for someone to take the latest version, make it compile
in the media_tree in drivers/media/staging and post the patch (just take care to keep
the correct copyrights, Signed-off-by's etc.) and I'll be happy to take it. This is
exactly what staging is for. I think it will greatly increases the chances of this
code being improved for mainline. And I'm happy to take both drivers as well, again,
that's what staging is for.

I've been thinking of doing this myself, but I just don't have the time.

Ideally this is done by the authors, but if they don't have time either then someone
else can do this.

Regards,

	Hans